Underfeed stoker



jan, 13, 1925.

J. S. SKELLY v UNDERFEED sToKER Filed May l1, 1921 atented Jan. 13, 1925.

FEE.

JOHN S.v SKELLY, 0F MONONGAHELA, PENNSYLVANIA, ASSIGNOR TO INTERNATIONAL C0lllIl3US'lI01\` ENGINEERING CORPORATION, A CORPORATION OF DELAWARE.

UNDERFEED STOKER.

Application led May 11,

To all whom t may concern.

Be it known that I, JOHN S. SKELLY, a citizen of the United States, and a resident of Monongahela, in the county of Washington and State of Pennsylvania, have made la new and useful Invention in Underfeed Stokers, of which the following is a speciication.

This invention relates to furnaces and particularly to mechanically-operated stokers in which mechanical means are empllyed for feeding the fuel into the furnace an propelling it over .the fuel supporting surfaces thereof.

A n object of the invention is to provide a Stoker of the type specified in which the fuel delivered to the furnace is rst subjected to preliminary distillation within a retort and is subsequently burned as it moves toward the rear of the furnace over fuel supporting elements such as grate bars.

A further object is to produce such a stoker in which improved means are employed for delivering fuel to the furnace, for propelling it therethrough and for effectively controlling combustlon throughout the fuel bed.

A further object is to produce a stoker in which effective means are employed for controlling the contour of the fuel bed.

These and other objects areattained by means of apparatus embodying the features herein described and illustrated in the drawings accompanying and forming a part hereof.

In the drawings, Figure 1 is a diagrammatic, longitudinal sectional view of a furnace embodying my invention. Fig. 2 is a fragmental sectional view illustrating in detail the construction employed for retaining stationary grate bars in place on the frame 1 of the Stoker.

The stoker illustrated is broadly similar, both in structure and in general mode of operation, to the stoker illustrated and described in my application Serial No. 398,897, filed IJuly 26, 1920. It, however, embodies certain features which occasion some variation in its operation and cause it to differ in details of construction from the Stoker illustrated in said a plication.

As shown, it incliides a retort 5 which extends across the front of the Stoker and is located immediately adjacent the front wall.

1921. Serial No. 468,650.

Fuel is fed to the retort 5 from one or more hoppers located at the front of the furnace. A passage 7 extending through the front wall 8 of the furnace, establishes communication between the hopper and the retort 5. One orr` more mechanically actuated plunger-s 9 operates to propel fuel from the hopper 6 through the passage 7 and into the retort 5. As shown, the passa e 7 is formed between a substantially flat oor plate 10 mounted o n and forming a part of the frame work of the stoker and an upwardly and rearwardly inclined plate or bracket 11 which forms a support for the upper portion of the front wall of the Stoker.

The Vertical width of the `inlet end of the passage 7 is so proportioned with relation to the vertical width and the location of the plunger 9 that a clearance substantially equal to the vertical width of the plunger is maintained between the upper face of the plunger and the upper edge of the inner end of the passage when the plunger is moved to its innermost position. As shown, the plunger is adapted to be reciprocated by a suitable operating mechanism in substantially the plane of the upper surface of the plate 10. With this arrangement, packing of the fuel traversing the passage 7 is prevented and the fuel is delivered to the retort in a more or less loose mass.

In the stoker illustrated, there is no clear line of division between the retort 5 and the passage 7. An upwardly and rearwardly.

inclined plate or fuel guide 13 extends longitudinally of the furnace and is so mounted with relation to the plate l0 that it forms, in effect, a portion of thefloor nand also the fuel discharging side of the retort. The forward ed e of this plate is mounted on and prefera ly secured to the plate 10 and the rear and upper edge overhangs a series of grate bars 14.

The grate bars 14 are hollow, are mounted on the frame of the Stoker in parallel relation and are downwardly' inclined toward the rear of the furnace. As disclosed in my previously-mentioned application for pat ent, this series of bars includes alternately arranged stationary and moving grate bars and co-operates with a second series of alternately arranged moving and stationary grate bars 15, which extend in parallel relation and are located between the first series and an ash pit or well 16 located adjacent to the bridge wall 17.

The forward ends of the bars of the senes 14 are supported by a transversely extending angle Vbar 18 forming a part of the framework of the stoker and located adjacent to but spaced from the retort 5. The lower ends of these bars are mounted on an L-shaped bracket 19 forming a part 'of the stoker and are so arranged that they overlap the forward ends of the second series of bars 15. The bracket19 is mounted on a partition plate 20 forming a part ofthe framework of the stoker and so located with relation to the bars and a front partition plate 21 that it divides the space below the two series of grate barsinto two air chambers 22 and 23. The forward ends of the second series of bars are mounted on a transversely extending bracket 24` forming a part of the frame work of the stoker and the lower ends of these bars are supported by a partition plate 25 intervening between the air chamber 23 and the ash pit or well 16.

In Fig. 2, I have illustrated means for holding the stationary bars of the series 14 in place. As there shown, the forward end of each stationary bar is provided with two downwardly extending lugs 26 which are arranged to straddle the upper flange of the angle bar 18. A similar arrangement may be employed in .connection with the stationary bars 15 and the bracket 24.

As stated, the grate bars are hollow and, as illustrated in my previously mentioned application, means are employed for circulating air through these bars for the purpose of cooling the bars and preheating the air prior to its delivery to the fuel bed. Each bar 14 is open at its forward end and communicates directly with an air` delivery passage 27 which. extends upwardly through the chamber 22 and includes the space between' the angle bracket'18 and the partition plate 21. The plate 13 also formsI a wall for this passage and is so arranged that it is subjected to the cooling action of the air traversing the passage just prior to its delivery to the grate bars. Each grate bar is provided vat its lower end and -in its bottom face\ with an air discharge port 29 communicating directly with the chamber 22. Air dellivery apertures 30 are formed in the upper face of each grate bar near the ,forward end of the bar. These apertures, together with air delivery apertures 31 formed inthe plate 13, co-operate to deliver air under pressure to the uel issuing from the retort 5 and moving onto the forward ends of the grate bars 14. As shown in the drawings, the apertures 31 are graduated so that they increase in size from the front to the rear of the stoken In this way an increasing amount of air is delivered to the fuel as the fuel moves onto the grate' bars 14. Each grate bar 15 is provided with air delivery apertures 32 formed in its upper face and located at its'forward end. An air delivery port 33 is formed in the lower face and is located near the lower end of each of these grate bars and is so arranged that it coinmunicates directly with the chamber 23..

Air-is delivered to inlet ports 34 formed in the bottom face at the forward end of each of these bars by means of a-'passage 35, which communicates with a separate source of air under pressure or with the passage 27. As shown, the passages 35 and 27 are provided with dampers 36, 361, so that the delivery of air under pressure ma beindependently controlled to the di erent portions of the fuel bed.

l have diagrammatically shown at 37 and 37 means for reciprocating the moving grate bars of the respective series 14 and 15. This operating mechanism is more fully described in 'my previously mentioned yap- 4 plication. The operation of the apparatus is as follows:

The reciprocations of the plunger 9l feeds r grate bars. As described in my earlierapplication, air unde-r Apressure passes through the air passages of the grate bars 14qand is delivered through the air ports 29 1nto the chamber 22 from which it passes pwardly between the bars to the fuel bed.

' The fuel on the grate bars 14 is subjected to the propelling and breaking action of the reciprocating bars and is finally delivered tothe grate bars 15. The reciprocation of the moving bars of this series also breaks u the fuel bed and propels the fuel rearwar ly toward the ash pit or well 16. Air under pressure is delivered to this portion of the fuel bed throu h the apertures 32 formed in the grate ars 15 and lso through the spaces between the grate ars. enters the air passages of the grate bars 15, a portion being delivered through the apertures 32 and the remaining being delivered to the chamber 23 t the air delivery ports 33. This air is preheated in its passage througr the bars and is delivered from the chamber 23 to The air delivered by the passage 35" portion roughpit or well 16 from which delivered by grinding rolls or a veyor.

While I'have described and illustrated but one embodiment of my invention, it will be apparent to those skilled in the art that various changes, modifications, additions and omissionsrmay be made in the apparatus without departing from the spirit and scope of the invention as set forth by the appended claim.

I claim as my invention:

In a Stoker, a front plate elevated at its rear edge to forml a retort extending across the front of the Stoker, a series of downwardly inclined hollow alternatel arranged moving and stationary grateb located in parallel relation and extending it may be spiral conars,

from th retort toward the rear of the Stoker, e ch grate bar having a forward portion extending substantially horizontally and open at its forward end and overlapped by said front plate, and a downwardly inclined portion having delivery apertures formed in the fuel supporting face thereof, and means for deliverm air under ressure'to the interiors of said ars, throng apertures formed in said plate and through the spaces between the bars.

In testimony whereof, I have hereunto subscribed my name this 30th day of April,

JOHN S. SKELLY. Witnesses:

E. C. LENHART, C. F. BowLBY. 

